DE68926378T2 - Image processing device and method - Google Patents

Description

The invention relates to an image processing apparatus such as a copying machine, a facsimile machine or the like having a counterfeit prevention function with which copying of bank notes or the like can be prevented, and a method therefor.

Until now, the purpose of image copying devices such as copying machines has been to faithfully reproduce images of an original placed on the device by reading it, according to a user's requirements.

Recently, as a result of the development of digital color copying machines, originals having a variety of colors and the color tones of the originals have been reproduced and recorded with great fidelity, the digital color copying machines being constituted by combining a color image pickup device using a charge-coupled device (CCD) or the like with a digital color printer such as a laser beam printer, an ink jet printer or the like. Therefore, it is possible to easily counterfeit papers or printed matter such as banknotes, bank notes or securities, the copying of which is prohibited.

However, the conventional copying machines have not been equipped with a device to prevent copying of banknotes, securities and important printed matter. Furthermore, no machine is capable of using securities or banknotes as copy-protection devices according to a user's requirements. To register printed matter to prevent copying or to change the copy function of the device.

This causes a problem in that banknotes or securities whose copying must be prevented can be used as a new pattern. Another problem arises in that if the format of a security is changed, a permanent memory in which, for example, copy-protection printed matter is stored must be updated.

JP-A-60-229572 discloses an image processing apparatus in which the brightness distribution of paper money is stored in a directory part and the correlation between the brightness distribution of input data and that in the directory is compared. If the correlation value exceeds a threshold value, copying is prohibited.

According to a first aspect of the invention, there is provided an image processing apparatus having a forgery prevention function which is adapted to prevent a faithful reproduction of an input image if it is determined that the input image is a specific reference image, the apparatus comprising a storage device for storing reference data characteristic of the reference image, an input device for receiving input data characteristic of the input image, and a comparison device which compares the input data with the reference data to decide whether the input image corresponds to the specific reference image and which generates a signal for preventing the faithful reproduction of the input image, and the apparatus is characterized in that at least a part of the storage device is writable and in that the apparatus further comprises a reference data writing device operable by an operator for writing in new reference data which is characteristic of a further specific reference image are stored in the storage device.

An embodiment of the invention provides an image processing apparatus capable of independently storing arbitrary papers and printed matters according to a user's request to prevent their copying.

An embodiment of the invention provides an image processing apparatus comprising input means for inputting image data, storage means for storing the image data inputted by the input means as reference data, and control means for controlling image processing according to the image data inputted by the input means and the reference data stored in the storage means. Accordingly, image data of an original whose copying a user wishes to prevent, for example, is read for storage in the storage means as reference data. The image data obtained from the reading means during a normal image forming process is then subjected to comparison with the reference data stored in the storage means. If it is determined that the original contains the same image pattern as that according to the reference data, the image processing is controlled according to the result of the determination.

If copy-protected printed matter can be stored individually, a problem arises in that printed matter whose copying must be prevented may be copied by misusing the arrangement designed to easily carry out the updating or deletion of the storage. For example, if a copy-protected printed matter is stored by a user, another person may re-enter the data relating to the printed matter and thus the printed matter cannot be be identified as a printed matter whose copying is prohibited.

A second aspect of the invention provides a method of operating an image processing apparatus which prevents accurate output of an input image when it is decided that the input image is a specific reference image based on a comparison between stored reference data and input data, the method comprising the steps of: (a) deciding whether an operator is authorized to change the reference data in order to restrict the persons who can change the reference data, (b) setting the apparatus in a state for changing the reference data in accordance with a decision result in the decision step, (c) deleting first reference data relating to an original of a first type which has been stored and used for comparison, and (d) storing second reference data relating to an original of a second type different from the original of the first type in the apparatus.

An embodiment of the invention provides an image processing apparatus capable of properly controlling the printed matter stored as a copy-protected printed matter.

Other features of the invention will become apparent from the following detailed description of examples.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a block diagram illustrating the basic configuration of a first embodiment of the invention.

Fig. 2 is a schematic representation of the internal configuration of the whole main part of the first embodiment of the invention.

Fig. 3 is a plan view showing an example of the external configuration of the control panel shown in Fig. 2.

Fig. 4 is a plan view showing an example of the external design of the digitizer shown in Fig. 2.

Figs. 5A and 5B are plan views showing examples of displays on the screen when storing the copy lock according to the first embodiment of the invention.

Fig. 6 is a block diagram illustrating the structure of a circuit for use in the control unit shown in Fig. 2.

Fig. 7 is a flowchart illustrating the process for controlling copy-protection storage according to the first embodiment of the invention.

Fig. 8 is a plan view showing a printed matter stored for preventing copying and a storage area.

Fig. 9 is a plan view showing an example of a display on the screen when determining that copying of the printed matter in question is prohibited according to the first embodiment of the invention.

Fig. 10 is omitted.

Fig. 11 is omitted.

Fig. 12 is a block diagram illustrating the basic configuration of a second embodiment of the invention.

Fig. 13 is a plan view showing an example of the external configuration of the digitizer according to the second embodiment of the invention.

Figs. 14A to 14K are illustrations of displays displayed when a stored image is changed or deleted.

Fig. 15 is a block diagram of a circuit for use in a control unit.

Fig. 16 is a flowchart corresponding to a memory image change mode.

Figs. 17A and 17B are views showing displays on the screen according to a third embodiment.

Fig. 18 is a block diagram showing the structure of a circuit for use in a control unit according to the third embodiment of the invention.

Fig. 19 is a flowchart corresponding to a memory image change mode.

Fig. 20 is a plan view showing the external configuration of an operation panel with a card reader.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the drawings, preferred embodiments of the invention will now be described in detail.

< First example>

Fig. 1 is a diagram illustrating the basic configuration of a first embodiment of the invention. In Fig. 1, A denotes an area designating means for designating an arbitrary area of an original image. B denotes a data converting means for reading original image data relating to an area designated by the area designating means A and converting it into image pattern data. C denotes a storage means for storing the image pattern data converted by the data converting means B in accordance with a storage instruction, the image pattern data being stored as reference data. D denotes a comparing means for comparing between the image pattern data obtained from the data converting means B and the reference data stored in the storing means C, the comparison being made when an image is formed. E denotes a control means adapted to terminate the image forming process in accordance with the result of the comparison by the comparing means D.

Fig. 2 is a schematic diagram of the internal configuration of a digital color copying machine according to the first embodiment of the invention. The machine according to this embodiment includes a digital color image reading device 1 (hereinafter referred to as "color reader") in its upper part and a digital color image printing device 2 (hereinafter referred to as "color printer") in its lower part. The color reader 1 reads color image information of an original corresponding to colors by a color separation device and photoelectric conversion elements such as charge-coupled devices (CCD) for converting the information into an electric digital image signal. The color printer 2 is an electronic-photographic (or electrophotographic) laser beam color printer for reproducing the color images corresponding to the Colors in response to the digital image signal and for recording them by transferring them with digital dots onto a sheet of recording paper.

First, the color reader 1 is described schematically.

Denoted at 3 is an original, 4 is a glass plate on which the original 3 is placed, and 5 is a rod lens assembly which collects image light reflected from the original 3 which is illuminated and scanned by an exposure lamp 10 and inputs the image light into a 1:1 full-color sensor 6. Denoted at 7 is a sensor output signal amplifier circuit. These elements 5, 6, 7 and 10 together constitute an original scanning unit 11 which illuminates the original 3 and scans it in the direction shown by an arrow A1.

The color image signals separated by colors read as a result of illumination and scanning for each of the lines are amplified to a predetermined voltage level by the sensor output signal amplifier circuit 7 and supplied via a signal line 501 to a video processor 12 in which the signals are processed. The signal line 501 is a coaxial cable that enables reliable signal transmission. 502 designates another signal line through which pulses for driving the 1:1 full-color sensor 6 are supplied, all of the driving pulses being generated in the video processor 12.

Reference numerals 8 and 9 designate a white plate and a black plate, with which the white level and the black level of the image signal are corrected in such a way that the white plate 8 and the black plate 9 are irradiated with the halogen exposure lamp 10 to obtain a signal level for a predetermined density from the 1:1 full-color sensor 6, the signal thus obtained Signal level is used for white level and black level compensation (or correction).

13 designates a control unit (control device) that contains a microcomputer. The control unit 13 controls all operations carried out in the color reader 1. The control unit 13 controls the display on a control panel 20, the key input via this and the function of the video processor 12 via a bus 508. The control unit 13 causes the position of the original scanning unit 11 to be detected by position sensors S1 and S2 via signal lines 509 and 510. Furthermore, it controls a stepper motor driver circuit 15 for the pulse drive of a stepper motor 14 for moving the original scanning unit 11 via a signal line 503. Furthermore, the control unit 13 controls the switching on and the amount of light of the halogen exposure lamp 10 via a signal line 504 by means of an exposure lamp driver stage. Furthermore, it controls the functions of internal keys and the function of the display part via a signal line (bus line) 505 on a digitizer 16.

The color image signal read by the original scanning unit 11 when illuminating and scanning the original is supplied to the video processor 12 via the amplifier circuit 7 and the signal line 501, where it is subjected to a variety of processing before being supplied to the color printer 2 via an interface circuit 56.

The color printer 2 is described schematically below.

711 denotes a deflection unit which includes a laser output part (not shown) for converting the image signal supplied from the color reader 1 into an optical signal, a polygon mirror (for example, octagon mirror) 712, a motor (not shown) for rotating the mirror 712 and an fθ lens (imaging lens) 713. 714 denotes a reflection mirror for changing the optical path traversed by the laser beams and 715 denotes a photosensitive drum. The laser beam emitted from the laser emitting part is reflected by the polygon mirror 712 and then passes through the lens 713 and the mirror 714 before linearly scanning the surface of the photosensitive drum 715 (for raster scanning). As a result, a latent image corresponding to the original image is formed.

717 denotes a primary charger, 718 denotes a total exposure lamp, 723 denotes a cleaning member for toner remaining after the transfer operation, and 724 denotes a pre-transfer charger, these elements being arranged around the photosensitive drum 715.

726 denotes a developing unit for developing the static latent image created on the surface of the photosensitive drum 715 by exposure to the laser. 731Y, 731M, 731C and 731BK denote developing cylinders designed for direct development in which they are brought into contact with the photosensitive drum 715. 730Y, 730M, 730C and 730BK denote toner reservoirs in which toner supplies are housed. 732 denotes a screw for conveying the developer. Thus, the developing unit 726 is composed of the above-mentioned cylinders 731Y to 731BK, the toner reservoirs 730Y to 730BK and the screw 732, these elements being arranged around a rotational axis P of the developing unit 726. For example, when a yellow toner image is formed, the yellow toner image is formed with the elements in the position shown. When a magenta toner image is formed, the developing unit 726 is rotated with respect to the axis P so that the developing cylinder 731M in the magenta developing device is brought into contact with the photosensitive drum 715. In a similar manner, a cyan toner image and a black toner image are formed.

716 is a transfer drum for transferring a toner image formed on the photosensitive drum 715 to a sheet of paper. 719 is a positioning plate for detecting the position of the transfer drum 716 after it has moved, and 720 is a position sensor for detecting that the transfer drum 716 has moved to its home position by bringing the position sensor 720 to the positioning plate 719. 725 is a transfer drum cleaning device, 727 is a paper holding roller, 728 is a discharger, and 729 is a transfer charger. These elements 719, 720, 725, 727, and 729 are arranged around the transfer drum 716.

735 and 736 denote paper supply cassettes for storing paper (paper sheets), 737 and 738 denote feed rollers for feeding paper from the paper supply cassettes, and 739, 740 and 741 denote timing rollers for timing the paper feeding and conveying operations. The paper sheet that has passed over these elements 735 to 741 is guided by a paper guide 749 while being held at the front portion by a holding device. Then, it is wound around the transfer drum 716 before being transferred to an image forming process.

550 is a drum rotation motor for synchronously rotating the photosensitive drum 715 and the transfer drum 716. 750 is a stripping pawl for releasing the paper sheet from the surface of the transfer drum 716 after the completion of the image forming process. 742 is a conveyor belt for conveying the paper sheet thus released, and 743 is an image fixing part in which the paper sheet fed by the conveyor belt 742 The image fixing part 743 includes a pair of heat pressure rollers 744 and 745.

Fig. 3 is a diagram showing the control panel 20 of the color copying machine in detail. In Fig. 3, 400 is a copy start key (copy key) for instructing the start of a copying operation, 401 is a reset key for returning the current mode to the standard mode, 402 is an enter key for instructing a storage mode or a maintenance mode, 404 is a ten-key key for entering numbers such as the instructed number of sheets of paper, and 403 is a clear/stop key used when the entered number is to be cleared or when the operation is to be interrupted during a continuous copying. 405 is a liquid crystal display and a touch panel for displaying a state of the printer 2 and for instructing an operation mode.

407 denotes a center shift key, and 408 denotes an original detection key designed to automatically detect the size and position of the original during copying. 406 denotes a projector key for designating a projector mode, 409 denotes a recall key for restoring the previous copying state, 410 denotes memory keys (M1, M2, M3 and M4) for storing or recalling the specified value programmed in advance for each mode, and 411 denotes a memory key for each of the memories.

Fig. 4 is a view illustrating the appearance of the digitizer 16 as an example of a device suitable for determining an area. In Fig. 4, 422 denotes a zoom button, 423 a displacement key, 424 an area designation key, 425 a color generation key, 426 an enlargement copy key and 427 an insert synthesis key. The above keys 422, 423, 424, 425, 426 and 427 are input keys each used to designate an operation mode. 420 is a coordinate detection plate (coordinate location detection plate) used to designate an arbitrary area on the original or to specify a magnification. 421 is a pointing pen for designating a coordinate on the coordinate detection plate 420. Information about the states of the keys 422 to 427 and the coordinate detection plate 420 and information about input coordinates are stored in a random access memory (RAM) in the control unit 13 by the central processing unit (CPU, the microcomputer) in the control unit 13 via the bus 505 shown in Fig. 2.

When an editing area is instructed on the original by a user, the area designation key 424 is first pressed. When the area designation key 424 is pressed, an area designation mode is initiated in which at least one area can be designated on the original, and an arbitrary mode selected from among the trimming, masking, image separation and copy-protection storage modes is instructed in each of the designated areas. The former three modes do not directly relate to the invention and the description of these modes is omitted. The copy-protection storage mode will now be described.

In the copy-protection storage mode, an image within an area commanded with the pointing pen 421 is read and, after being formed into image pattern data, is stored in a random access memory (RAM) 31 shown in Fig. 6 in the control unit 13. The data stored in the The data stored in the read/write memory 31 form a reference pattern such that no copying can be carried out if it is determined at the time of the copying operation that an image pattern under consideration is similar to this reference pattern.

A specific operation process in the copy-protection storage mode will be described below with reference to Figs. 5A and 5B.

When the area designation key 424 on the digitizer 16 is pressed, the display on the keypad liquid crystal display 405 on the operation panel 20 is replaced by a figure P300. As shown by this figure P300, a user places an original on the coordinate detection plate (editor) of the digitizer 16 and designates an area with the pointing pen 421.

When two points in the area are pressed, the display on the liquid crystal display 405 is replaced by a figure P310. If the user determines that the selected area is correct as shown by this figure P310, the user presses the touch key a (OK key) on the figure P310. When this touch key a is pressed, the display on the liquid crystal display 405 is replaced by a figure P320.

Then, the user selects a process for the specific area from the displayed processes, namely, cropping, masking, image separation and copy-protect storage, and presses a key corresponding to the selection result.

When the user sets the copy lock storage mode, the display returns to the liquid crystal display 405 returns to the image P300 and the area determination is then carried out.

After the designation of all the areas to be stored for preventing copying is completed by repeating the above-described processes, the user must place the original on the glass plate (copy frame plate) shown in Fig. 2 and press the copy key 400. As a result, a reference image pattern for the copy-prohibited original is stored in the RAM in the control unit 13 in the manner described below.

Fig. 6 illustrates the structure of a circuit for use in the control unit shown in Fig. 2. In Fig. 6, 22 denotes a central processing unit CPU which, according to this embodiment, carries out a control process as shown in Fig. 7. 23 denotes a read-only memory ROM in which the control sequence and constants are stored in advance, and 24 and 25 denote random access memories RAM which serve as work areas for the central processing unit 22. 26 denotes an input/output unit via which a control signal is sent from the central processing unit 22 to a light control lamp driver stage 21 which is designed to operate the halogen exposure lamp 10. 29 denotes a serial interface with which data is transmitted to and received from the digitizer 16. 27 denotes an interrupt control unit, and 28 denotes a timer circuit. 30 is an image pattern processor for generating image pattern data in the selected area by binary digitizing or the like. 31 is the register RAM which stores the image pattern data generated by the image pattern processor 30 as reference data (reference image pattern data) when the current mode is the copy-protection storage mode. 33 is a comparison RAM for storing data developed into pattern data by the pattern processor 30 during the pre-scanning time in an ordinary copying mode, and 32 is a comparator circuit which compares the original pattern data stored in the RAM 33 with the reference data to determine the correlation therebetween. A control signal indicating the existence of a correlation output from the comparator circuit 32 is supplied to the central processing unit 22 via a signal line 34. The above-described elements 22 to 33, the video processor and the control panel 20 are connected to one another via the bus 508.

Fig. 7 illustrates a control procedure executed by the central unit 22 in the control unit 13 for the copy-protection storage described above.

Upon pressing the copy button 401, the halogen exposure lamp 10 is turned on in a step S100. Then, in a next step S101, the black level correction is carried out. After that, in a step S102, the white level correction is carried out.

Then, the flow advances to a step S103, where an operation mode for reading the area determined in advance by the digitizer 16 starts. In this operation mode, the image data subjected to the black level correction and the white level correction by the video processor 12 shown in Fig. 6 are transferred to the image pattern processor 30 shown in Fig. 6 via the bus 508. The image pattern processor 30 carries out, for example, binary digitization. Thus, data after the binary digitization is stored as reference data in the RAM 31 shown in Fig. 6. Then, in a step S104, the halogen exposure lamp 10 is turned off, thus ending the storage process.

The area to be stored by a user will now be described in detail. If copying of a printed matter marked with a "SECRET" mark as shown in Fig. 8 is prohibited, it is necessary to specify a frame shown by a dashed line in Fig. 8 and indicated by (A) with the pointing pen 421 in order to store this area (A) in the form of reference data in the aforementioned RAM 31. The area indicated by the dashed line in Fig. 8 indicates the fact that letters are written.

In the normal copying state, image data of the original is transferred to the image pattern processor 30 during pre-scanning, and the image data thus transferred is then binary-digitized for storage in the random access memory 33 in the same way as described above.

The image pattern data for the original thus stored in the RAM 33 is transferred to the comparator circuit 32, where it is compared with the reference data (reference image pattern data) previously stored in the RAM 31. For this comparison, for example, a value L according to the following equation (1) is used:

where i, j : picture element number

n, m : Number of picture elements in the reference picture pattern data

p, q: number of shifts

xij : Value of reference image pattern data at (i, j)

Xij : Value of the original image pattern data at (i, j)

If the value obtained from the comparison satisfies the following relationship:

L > Lth (2)

where Lth is a threshold value, the comparator circuit 32 determines that the original image pattern data contains the same image pattern as the reference image pattern. As a result, the comparator circuit 32 outputs a control signal (copy inhibit control signal) to the CPU 22 via the signal line 34.

When the central processing unit 22 receives the copy inhibit control signal, it aborts the copying operation and causes a message shown in Fig. 9 to be displayed on the display 405 on the control panel 20 to inform the user that copying is inhibited.

If the value L obtained from the calculation according to equation (1) satisfies the following relationship:

L ≤ Lth (3)

the comparator circuit 32 determines that the same image pattern as the reference image pattern is not included in the original image pattern data, so that it does not supply the copy inhibit control signal to the central processing unit 22. As a result, the central processing unit 22 carries out a normal copying operation.

As described above, in this embodiment, since the images of, for example, bank notes or securities whose forgery must be prevented can be inputted by means of the image input device used for a normal copying operation, the storage or modification of the image whose forgery must be prevented can be carried out extremely easily.

As described above, in the first embodiment, an area of an original which a user desires to be prohibited from being copied is unconditionally specified by the area specifying means. In accordance with the storing instruction, the data on the specified area is read and converted into pattern data by the data converting means. The data thus converted is stored in the storage means as reference data, which is subjected to comparison with the read-out pattern data available from the data converting means during normal image formation. When it is determined that the original contains the same pattern as that of the reference data, the control means automatically terminates the image formation process. As a result, the arrangement is designed to prevent copying of important papers such as secret documents which a user desires to be prohibited from being copied in a simple and reliable manner.

While the arrangement is designed such that the image formation is stopped when a particular original is detected, another arrangement may be used which is designed such that the content of the image formation process is changed from that for an ordinary original while the image formation process is continued. For example, if a copy-lock original is detected, an all-black image may be output. Alternatively, another monochrome image may be output. Further, an all-black image may be formed in a partial area or over the entire area of the image area. This processing can be carried out by always setting the black data BK input to the printer from the control device E shown in Fig. 1 to "1" in accordance with the output signal from the comparison device D shown in Fig. 1. or all magenta data M, yellow data Y and cyan data C are set to "1".

< Second embodiment>

The image processing device according to this embodiment is characterized in that a device for updating, supplementing and deleting reference data is also provided.

Fig. 12 is a block diagram illustrating the overall structure of the image processing apparatus according to this embodiment.

In Fig. 12, A' is an image data input device, B' is a reference data storage device for storing reference data, C' is a comparison device for comparing input data with the reference data stored in the reference data storage device B', D' is a control device for outputting a copy inhibit signal as a control signal according to the result of the comparison by the comparison device C', and E' is a reference data changing device for adding, changing and deleting reference data. F' is a data converting device for converting image data input by the input device A', and G' is an area determining device for setting a predetermined area for the input image.

The schematic internal structure of the image processing apparatus according to this embodiment is similar to that shown in Fig. 2 and the operation panel is also designed in a similar manner to that shown in Fig. 3. Therefore, the description of these arrangements is omitted here.

Fig. 13 shows the configuration of the digitizer 16 which serves as an example of the area designating means. In Fig. 13, 422 is a zoom key, 423 is a displacement key, 424 is an area designating key, 425 is a color generation key, 426 is a magnification copy key, 427 is an insert synthesis key, and 428 is a memory image change key. The keys 422, 423, 424, 425, 426, 427 and 428 are input keys for instructing a respective operation mode. 420 is a coordinate detection plate (coordinate location detection plate) for designating an arbitrary area on an original or for prescribing a magnification. 421 designates a pointer pen with which coordinates are entered on the coordinate acquisition plate 420. The information via the keys 422 to 428 and the coordinate acquisition plate 420 as well as the entered coordinate information are stored by the central processing unit CPU (microcomputer) in the control unit 13 via the bus 505 according to Fig. 2 in the read/write memory RAM in the control unit 13.

Since the first six operating modes brought about by means of these keys are not directly related to the invention, a detailed description is omitted here.

The operation of this embodiment will now be described in that the reference data changing means E' is largely like that described with reference to Figs. 1 to 9.

First, the operation will be described. As described above, when an attempt is made to copy a printed matter whose copying is prohibited, a message shown in Fig. 9 is displayed. In this case, it is determined that for a certain area in a printed matter whose copying is attempted, as a result of comparison by the comparison device C' the data is the same as the reference data previously stored in the reference data storage device B'. As a result, a copy inhibit signal is output from the control device D'.

The procedure for adding, changing and deleting the reference data stored in the reference data storage device B' is shown in Figs. 14A to 14K.

If the user intends to change the reference data that has been previously stored, the user must press the memory image change key 428. In this case, the display 405 on the liquid crystal display/touch panel of the operation panel 20 changes to a message shown in Fig. 14A.

Then, for data to be read and inputted by the image data input device A', a secret number such as "3356294" is inputted from the ten-key pad 404 shown in Fig. 3 and compared with secret numbers previously stored in the read/write memories 24 and 25 in the control unit 13. If the numbers do not match, the message is replaced by that shown in Fig. 14B. The secret number serves as a personal identification code for a person authorized to change the stored image. If no input is made for a predetermined period of time, a message shown in Fig. 14C is displayed on the display 405.

If the PIN number entered with the ten-key pad 404 and the PIN number previously stored are the same, a message as shown in Fig. 14D is displayed on the display 405. If the reference data is to be changed or added, the change storage key 450 must be pressed. If the reference data is to be deleted, the clear key 451 must be pressed. When the change storage key 450 is pressed, a message as shown in Fig. 14E is displayed. In this embodiment, as shown in Fig. 14E, a No. [1] is displayed in negative, which represents the fact that the reference data is recorded and stored only in the storage area No. 1. When the key [1] is pressed, the reference data No. 1 is erased and an input message for the reference data No. 1 shown in Fig. 14F is displayed.

According to the message displayed in the figure, the user must place the original on the coordinate detection plate (editor plate) 420 of the digitizer and specify and input an area with the pointing pen 421. As a result, a message shown in Fig. 14G is displayed. When two points are pressed in the area, the display is replaced by a message shown in Fig. 14H. Then, by pressing the OK key, the storage of reference data begins in accordance with an input of a new copy inhibit image. The storage of the reference data is carried out in the same manner as the storage in the first embodiment described above. In this way, new reference data is recorded as reference data No. 1 and stored by the reference data storage device shown in Fig. 12. When the clear key 451 shown in Fig. 14D is pressed, a message shown in Fig. 14I is displayed. Similarly to the case described above, the key No. 1 is displayed in negative to represent that the reference data is recorded and stored only in the storage area No. 1. When the key [1] is pressed, the message shown in Fig. 14K is displayed, and pressing the OK key deletes the reference data No. 1. When an all-clear key 452 is pressed, a message shown in Fig. 14J is displayed, and pressing the OK key deletes all the reference data.

Referring to Fig. 15, the structure and function of the control unit according to this embodiment including the storage device B', the comparison device C', the copy inhibit device D' and the reference data changing device E' will now be described.

Fig. 15 is a diagram showing the arrangement of the circuit for use in the control unit shown in Fig. 12. In Fig. 15, 22 denotes the CPU, 23 the ROM in which the control procedure and various constants are stored in advance, and 24 and 25 the RAMs which serve as working memories for the CPU 22. 26 denotes the input/output unit through which a control signal is transmitted from the CPU 22 to the light control lamp driver 21 for operating the halogen exposure lamp 10, 29 denotes the serial interface for transmitting data to and receiving data from the digitizer 16. 27 denotes the interrupt control unit, and 28 denotes the timer circuit. 30 is a data input circuit for encoding input data into code data, 31 is a register RAM for storing reference data, and 33' is a reference data changing device for controlling the RAM 31 in the event that the user intends to change the reference data. 32 is the comparator circuit which serves as a data comparing device C' for comparing between the coded reference data in the RAM 31 and the coded video signal to determine the correlation between the two data items. The control signal which is output from the comparator circuit 32 to indicate the fact that the correlation exists is fed via the signal line 34 to the central unit 22 which serves as a copy-protection control device D'. The above-mentioned elements 22 to 33', the Video processor 12 and control panel 20 are connected to each other via bus 508.

The operations for adding, changing and deleting reference data carried out by the reference data changing device 33' will now be described.

To start the reference data changing device 33', the memory image changing key 428 shown in Fig. 13 is pressed. The message shown in Fig. 14A is then displayed and a state of waiting for a code number is established. The operations will now be described with reference to the flow chart in Fig. 16. When a specific code is input from the ten-key pad 404 shown in Fig. 3 (S102), it is determined whether the code thus input is the same as that previously stored in the reference data changing device 33' (S103). If it is determined that the two codes do not coincide with each other, the flow advances to a step S104 where the message shown in Fig. 14B is displayed on the display 405, after which the operation ends. If it is determined that the input code and the stored code agree with each other, the message shown in Fig. 14D is displayed on the display 405 and a state is brought about in which a selection is awaited at a step S105. If a key input is made, it is determined whether the key pressed at that time is the one for changing or the one for deleting (S106). If it is determined that the key pressed is the one for changing, the message shown in Fig. 14E is displayed on the display 405 and a state is brought about in which the input of numerical values is awaited. The fact that the key [1] is displayed in negative indicates the fact that reference data has been stored in the memory area No. 1 and also the fact that nothing is stored in the memory areas No. 2 to No. 16. If No. 1 is commanded, the data stored in the memory area No. 1 is erased and an operation for storing new reference data is initiated. When any of No. 2 to No. 16 is instructed, the operation for storing new reference data is immediately initiated. Since the storing operations in steps S108, S109 and S110 were previously described in the first embodiment, a detailed description is omitted here. In this way, new reference data is stored in the RAM 31.

If it is determined that the key input during the display of the message shown in Fig. 14D instructs deletion, the flow advances to a step S111, where the message shown in Fig. 14I is displayed. The negative display of the key [1] indicates the same condition as that described above. If the key input instructs all deletion, the message shown in Fig. 14J is displayed, while if the enter key is the No. 1 key, the message shown in Fig. 14K is displayed. Then, in a step S112, it is determined whether or not the input is made with the OK key. If the input is made with the END key, the operation is terminated without making the deletion. If the input with the OK key is detected, the flow advances to a step S113, in which the reference data stored in the RAM 31 is deleted according to the instruction issued by the reference data changing device 33'.

< Third embodiment>

Referring to Figs. 17 to 20, the configuration of the image forming apparatus according to this embodiment will now be described as a modification example.

According to Fig. 18, the control unit 13 contains the RAM 31 and an operation card reader 41. The other arrangements are similar to those shown in Fig. 15.

When the memory image change key 428 shown in Fig. 13 is pressed, a message shown in Fig. 17A is displayed on the display 405. Fig. 20 illustrates the configuration of the operation part, in which 401 to 411 denote the same elements as those shown in Fig. 3. 430 denotes an IC card in which reference data is stored and which is shown in a state in which it is inserted.

When a user inserts the IC card 430 shown in Fig. 20 into the operation card reader 41, it is determined whether the IC card 430 is a correct IC card. If it is determined that the IC card is correct, the reference data changing means 33' transfers all the reference data stored in the IC card 430 to the read/write memory 31. According to this modification, the IC card 430 can store the reference data corresponding to the desired state. Therefore, by strictly controlling (or supervising) the use of the IC card, a change or deletion of the stored reference data cannot be easily carried out. Since the process for determining whether the subject printed matter is the copy-protected printed matter or not is carried out in a similar manner to the foregoing embodiments by referring to the reference data stored in the RAM 31, the description is omitted here.

If an incorrect IC card is inserted, a message shown in Fig. 17B is displayed on the display 405 and storage of new reference data is prohibited.

Although the IC card serves as a recording medium in which the reference data is stored in the third embodiment, it may be used as an IC card that allows the change, addition and deletion of the reference data as an alternative to the code. A flowchart corresponding to this case is shown in Fig. 19. The difference from the flowchart shown in Fig. 16 is a step S201. Since the other steps are the same as those shown in Fig. 16, the description is omitted here.

As described above, in the second and third embodiments of the invention, in order to prevent easy rewriting, addition and deletion of the reference data designed for judging whether copying is prohibited or not, various means and arrangements are used such that a code (or secret number) is used, reference data is stored by means of a card in which the reference data has been stored in advance, or rewriting, addition and deletion of the reference data is permitted by means of the card. Therefore, an excellently satisfactory effect of preventing an excessive increase in the amount of copy-protected printed matter can be achieved. Furthermore, another satisfactory effect can be achieved in that the copy-protection cannot be easily canceled. Although in the above-described embodiments, the liquid crystal display/touch panel is used to indicate the numbers for changing the reference image, this can be done by using the ordinary keys.

As an alternative to the arrangement described above in which a plurality of reference data items can be rewritten, a part of the reference data can be stored in a read-only memory so that it cannot be rewritten. In particular, if the arrangement is designed in such a way that only a supplement to the reference data regarding banknotes, counterfeiting of old banknotes can be prevented.

Although the digitizer is used to determine an area in the previously described embodiments, the numeric keypad 404 can be used to determine the area by entering coordinates.

As an alternative to the binary data according to the above-described embodiments, the image pattern data to be stored may be data converted into multi-value data. As an alternative to the random access memory according to the above-described embodiments, the storage device may consist of a magnetic recording medium such as a floppy disk. The image processing may be changed according to the similarity (the proportion of coincidence) determined by the comparison between the reference data and the input image data as an alternative to the coincidence of the two data items according to the above-described embodiments.

- According to the embodiments described above, when it is determined that the input image is a predetermined image whose forgery must be prevented, the control means carries out control such that the image forming process is aborted or reversed, a monochrome image is output, or a completely black image is output. However, this may optionally be designed such that when a faithful reproduction of the image can be prevented, for example, special processing such as forming a mirror image or color change can be used, or the generated input image can be rendered unusable.

The device for permitting the alteration of the reference data acting to prevent forgery may be any device, provided that it is suitable for enabling a specific person to rewrite the reference data, such as an identification card (for example an optical card, a magnetic card or an IC card) or a code input device (for example a ten-key pad).

In the above-described embodiments, the laser beam color printer is used as the printer for outputting an image, but the printer is not limited to this. For example, a thermal color printer, an ink jet color printer, a matrix color printer or the like may be used.

Since many apparently widely different embodiments of this invention can be made without departing from the scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

Claims (19)

1. An image processing device with forgery prevention function, which is capable of preventing a faithful reproduction of an input image if it is determined that the input image is a specific reference image, and which a storage device (C-Fig. 1; 31; B'-Fig. 12) for storing reference data characteristic of the reference image, an input device (29; 508; A'-Fig. 12) for receiving input data characteristic of the input image, and a comparison device (B, D-Fig. 1; 30; 32; 33; C',F'-Fig. 12) which compares the input data with the reference data to decide whether the input image corresponds to the specific reference image and which generates a signal for preventing the faithful reproduction of the input image, characterized in that at least a part of the storage device is writable and that the device further contains a reference data writing device (22; 33') operable by an operator for writing new reference data which are characteristic of a further specific reference image into the storage device. 2. An apparatus according to claim 1, further comprising access control means (404; 22; 23; 24; 25; 430; 431) for preventing operation of the reference data writing means by unauthorized operators. 3. Apparatus according to claim 2, in which the access control means comprises a keypad code input device (404) and a means (22; 23; 24; 25) for comparing the code entered by an operator with pre-stored codes. 4. An apparatus according to claim 2, wherein the access control means comprises an ID card reader (431) and means for deciding whether an ID card (430) inserted by an operator is an acceptable ID card. 5. The apparatus of claim 3, further comprising a display device (405) for displaying a message representing the result of a comparison between the codes entered by an operator and the pre-stored codes. 6. The apparatus according to claim 4, further comprising a display device (405) for displaying a message indicating whether the ID card inserted by an operator is an acceptable ID card. 7. Apparatus according to any preceding claim, in which the reference data writing means is arranged such that the only change permitted to the reference data stored in the storage means is the addition of further reference data. 8. Apparatus according to any preceding claim, further comprising a reading device (1) for reading an image to be processed from an original and generating the input data therefrom. 9. Apparatus according to claim 8, in which the reading device includes a scanning unit (11), the reading device is operable to read the image to be processed during a pre-scanning operation and during a scanning operation, and the comparison device compares the input data generated during the pre-scanning process with the reference data. 10. An apparatus according to claim 8, with reference to any one of claims 1 to 3, in which the reference data writing device is designed such that the reference data to be stored in the storage device is input via the reading device. 11. An apparatus according to claim 10, operable to input the reference data to be stored in the storage means by reading a portion of an original placed on the reading device and generating the reference data therefrom. 12. An apparatus according to claim 11, comprising an area determining device (16) by which an operator can determine the part of the original. 13. Apparatus according to any preceding claim, in which the reference data comprises binary image pattern data. 14. Apparatus according to any preceding claim, wherein the reference data includes multi-valued image pattern data. 15. Apparatus according to any preceding claim, further comprising an image forming device (2) for forming an output image on a recording material from the input image data. 16. An apparatus according to claim 15, wherein the signal generated by the comparison means prevents accurate output image formation by controlling the image forming device. 17. An apparatus according to claim 15 or 16, wherein the image forming device is a laser beam printer. 18. An apparatus according to claim 15 or 16, wherein the image forming device is an ink jet printer. 19. A method for controlling an image processing device that prevents accurate output of an input image when it is decided that the input image is a specific reference image based on a comparison between stored reference data and input data, the method comprising the steps of (a) deciding whether an operator is authorized to change the reference data in order to restrict the group of persons who can change the reference data, (b) according to a decision result in the decision step, the device is set to a state for changing the reference data, (c) first reference data relating to an original of a first kind which have been stored and used for the comparison are deleted, and (d) second reference data relating to an original of a second type different from the original of the first type are stored in the device.